/*
 * Copyright (c) 1996, 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.io;


/**
 * A character stream that collects its output in a string buffer, which can
 * then be used to construct a string.
 * <p>
 * Closing a <tt>StringWriter</tt> has no effect. The methods in this class
 * can be called after the stream has been closed without generating an
 * <tt>IOException</tt>.
 *
 * @author Mark Reinhold
 * @since JDK1.1
 */

public class StringWriter extends Writer {

  private StringBuffer buf;

  /**
   * Create a new string writer using the default initial string-buffer
   * size.
   */
  public StringWriter() {
    buf = new StringBuffer();
    lock = buf;
  }

  /**
   * Create a new string writer using the specified initial string-buffer
   * size.
   *
   * @param initialSize The number of <tt>char</tt> values that will fit into this buffer before it
   * is automatically expanded
   * @throws IllegalArgumentException If <tt>initialSize</tt> is negative
   */
  public StringWriter(int initialSize) {
    if (initialSize < 0) {
      throw new IllegalArgumentException("Negative buffer size");
    }
    buf = new StringBuffer(initialSize);
    lock = buf;
  }

  /**
   * Write a single character.
   */
  public void write(int c) {
    buf.append((char) c);
  }

  /**
   * Write a portion of an array of characters.
   *
   * @param cbuf Array of characters
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   */
  public void write(char cbuf[], int off, int len) {
    if ((off < 0) || (off > cbuf.length) || (len < 0) ||
        ((off + len) > cbuf.length) || ((off + len) < 0)) {
      throw new IndexOutOfBoundsException();
    } else if (len == 0) {
      return;
    }
    buf.append(cbuf, off, len);
  }

  /**
   * Write a string.
   */
  public void write(String str) {
    buf.append(str);
  }

  /**
   * Write a portion of a string.
   *
   * @param str String to be written
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   */
  public void write(String str, int off, int len) {
    buf.append(str.substring(off, off + len));
  }

  /**
   * Appends the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.toString()) </pre>
   *
   * <p> Depending on the specification of <tt>toString</tt> for the
   * character sequence <tt>csq</tt>, the entire sequence may not be
   * appended. For instance, invoking the <tt>toString</tt> method of a
   * character buffer will return a subsequence whose content depends upon
   * the buffer's position and limit.
   *
   * @param csq The character sequence to append.  If <tt>csq</tt> is <tt>null</tt>, then the four
   * characters <tt>"null"</tt> are appended to this writer.
   * @return This writer
   * @since 1.5
   */
  public StringWriter append(CharSequence csq) {
    if (csq == null) {
      write("null");
    } else {
      write(csq.toString());
    }
    return this;
  }

  /**
   * Appends a subsequence of the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq, start,
   * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
   * exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.subSequence(start, end).toString()) </pre>
   *
   * @param csq The character sequence from which a subsequence will be appended.  If <tt>csq</tt>
   * is <tt>null</tt>, then characters will be appended as if <tt>csq</tt> contained the four
   * characters <tt>"null"</tt>.
   * @param start The index of the first character in the subsequence
   * @param end The index of the character following the last character in the subsequence
   * @return This writer
   * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are negative,
   * <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt> is greater than
   * <tt>csq.length()</tt>
   * @since 1.5
   */
  public StringWriter append(CharSequence csq, int start, int end) {
    CharSequence cs = (csq == null ? "null" : csq);
    write(cs.subSequence(start, end).toString());
    return this;
  }

  /**
   * Appends the specified character to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(c)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(c) </pre>
   *
   * @param c The 16-bit character to append
   * @return This writer
   * @since 1.5
   */
  public StringWriter append(char c) {
    write(c);
    return this;
  }

  /**
   * Return the buffer's current value as a string.
   */
  public String toString() {
    return buf.toString();
  }

  /**
   * Return the string buffer itself.
   *
   * @return StringBuffer holding the current buffer value.
   */
  public StringBuffer getBuffer() {
    return buf;
  }

  /**
   * Flush the stream.
   */
  public void flush() {
  }

  /**
   * Closing a <tt>StringWriter</tt> has no effect. The methods in this
   * class can be called after the stream has been closed without generating
   * an <tt>IOException</tt>.
   */
  public void close() throws IOException {
  }

}
